Inspired by this post I made in the "Fewer WWII Civilian Casualties" thread...
How do we get something like this to happen? Having the Japanese government hang everyone involved in the May 15 Incident might be a good POD to have a saner Japan that's still provoked China against it, but it's pretty late for Europe.
I do remember reading somewhere here there were millions of Germans willing to fight the Nazis as late as 1932-33, but the other parties lacked the spine. Maybe the leader of the Communist Party grows a brain, defies Stalin, and makes common cause with the Social Democrats. The Nazis go berserk, street fighting breaks out all over the country, and the Army has to "restore order." This they do--and in the process the leadership of the major German parties are killed and/or imprisoned--and whomever takes power in the aftermath (probably a military figure or puppet thereof) is our "Not Hitler."
However, someone who doesn't have Hitler's itch to rule over Slavs isn't going to take Bohemia and Moravia after promising not to make any more claims, which paved the way for Britain and France to declare war for Poland. That makes getting a war between the Western Allies and Germany tricky.
*A right-wing revanchist but non-psychotic-ideologue Germany might invade Poland for the Corridor and fight OTL's Western and Scandinavian campaigns to make sure they keep it. Invading the USSR is harder, but they could have a falling-out over the division of Poland or Not-Hitler could decide to launch a pre-emptive strike on Stalin for reasons other than LEBENSRAUM!1!1!
Without Nazism there's drastically less anti-Semitism and anti-Slavic racism, so there's no Holocaust and the campaign against the USSR is less brutal. It might also be a lot shorter--either Not-Hitler is content with setting up a puppet Ukraine 1918-style, which would deprive the Soviets of much of their heavy industry and the grain they exported to fund it and push the Soviets back, or the Wehrmacht is carried to Moscow by anti-Stalin Soviets who haven't been tyrannized into jumping back into Uncle Joe's arms.
(The latter might be really pushing it, as there's still the "foreign invader" problem and the fact the Soviet public might still love Communism even if they're not fans of Stalin. For all his horrors, there were still a LOT of people who believed in that whole "work hard to build a new society" thing.)
*At some point the Japanese manage to get their junior officer corps under control, but a lot of the damage has already been done--i.e. Manchuria is under Japanese control and possibly some of the earlier incidents have happened. Perhaps a harsher response to this that neuters the Japanese military's extremist elements. Sino-Japanese War, but on a different timetable--perhaps the Chinese spend years building up and attack Manchuria. Stronger Nationalists mean no epic Japanese victories and the atrocities they made possible (i.e. the Rape of Nanking), even if neutralizing the junior officers doesn't get rid of the brutalization of the lower ranks.
Now, getting the US involved in both of these wars--which helped make them World Wars as opposed to the Second Great War or the Second Sino-Japanese War--without flaming maniac ideologues at the helm of the *Axis is trickier but might still be doable.
*The US still has interests in China and won't approve of Japan closing the Open Door, although there won't be as much popular outrage without the Rape of Nanking or some equivalent. There could still be a Pearl Harbor attack, since Yammamoto and friends know time is against them and only something radical like that MIGHT ensure victory.
However, with saner leadership in Tokyo and (possibly) a less brutalized soldiery, you might avoid things like the Bataan Death March and other Japanese war crimes, which encouraged American soldiers to retaliate and made the Pacific War so brutal. If the Japanese military retains its WWI respect for prisoners and general (relative) pleasantness, the US might not be willing to fight a war unto death even with Pearl Harbor.
*The US would support Britain against a return of "Prussianism," the Junkers, etc. During the war a lot of people thought Hitler was a puppet of the WWI villains, so even without the horrors of fascism, the exodus of Jewish and other refugees, etc., there might still be hostility toward a revanchist Germany. A few Reuben James type incidents and the US and Germany are at war.
How do we get something like this to happen? Having the Japanese government hang everyone involved in the May 15 Incident might be a good POD to have a saner Japan that's still provoked China against it, but it's pretty late for Europe.
I do remember reading somewhere here there were millions of Germans willing to fight the Nazis as late as 1932-33, but the other parties lacked the spine. Maybe the leader of the Communist Party grows a brain, defies Stalin, and makes common cause with the Social Democrats. The Nazis go berserk, street fighting breaks out all over the country, and the Army has to "restore order." This they do--and in the process the leadership of the major German parties are killed and/or imprisoned--and whomever takes power in the aftermath (probably a military figure or puppet thereof) is our "Not Hitler."
However, someone who doesn't have Hitler's itch to rule over Slavs isn't going to take Bohemia and Moravia after promising not to make any more claims, which paved the way for Britain and France to declare war for Poland. That makes getting a war between the Western Allies and Germany tricky.